What part of the truck doesn't burn?

Aluminum does burn, if it gets hot enough, at over 2000 degrees F.

Way back when, 2005 probably, a driver I was acquainted with had a head on collision with a pickup driven by a young man who had left a suicide note, iirc, and was pulling a new reefer, with machine parts loaded, the tractor and the trailer burned to the ground, leaving the ferrous metal and the cargo in a pile of ash as the only things that didn't burn.

I was next to one at about that time, that went up while the driver was inside the diner, there was some frantic searching for that driver until he saw the commotion and realized it was his truck that had burnt up.

The fire department kept the trailer from going up, it was loaded with aerosol paint cans. Too close for comfort. This was pre emissions time period.